Electroacupuncture Combined with Intracerebral Injection of VEGF Improves Neurological Dysfunction Possibly by Down-regulating Expression of Endoplasmic Reticulum Stress Related Proteins ATF 6, etc. in Cerebral Ischemia-reperfusion Injury Rats

Abstract

To observe the effect of electroacupuncture (EA) and EA combined with intracerebral injection of vascular endothelial growth factor (VEGF) on endoplasmic reticulum stress (ERS) related proteins and genes as activating transcription factor (ATF 6), inositol requiring enzyme-1 (IRE 1), CCAAT/enhancer binding protein homologous protein (CHOP), X box-binding protein-1 (XBP 1) of cerebral ischemia reperfusion injury (CIRI) rats, so as to study its repair effect for CIRI. Forty male SD rats were equally and randomly divided into 5 groups: sham operation, model, EA, VEGF and EA+VEGF groups (n=8). The CIRI model was established by occlusion of the middle cerebral artery (MCAO) with thread embolism method. For rats of the sham operation group, the right common carotid artery was isolated without MCAO. EA (2 Hz/100 Hz, 1-3 mA) was applied to "Baihui" (GV 20), left "Quchi" (LI 11) and left "Zusanli" (ST 36) for 30 min, once a day for 14 days. For rats of the VEGF and EA+VEGF groups, 10 µL VEGF (0.025 µg/µL) was injected into the lateral ventricle 24 h after successful modeling. The rats' neurological function was assessed by using the modified neurological severity score (mNSS), and the histopathological changes of cerebral tissue were observed by Nissl staining method. The expression levels of ERS related proteins and genes ATF 6, IRE 1, XBP 1 and CHOP were determined by western blot (WB) and fluorescent quantitative PCR, separately. After modeling, the level of mNSS was significantly higher in the model group than in the sham operation group (P<0.05), and the number of Nissl bodies was markedly lower in the model group than in the sham operation group (P<0.05). Following the treatment, the mNSS was significantly lower in the EA, VEGF and EA+VEGF groups than in the model group (P<0.05), and the numbers of Nissl bodies were obviously higher in the EA, VEGF and EA+VEGF groups than in the model group (P<0.05), suggesting an improvement of neurological dysfunction and a repair of the injured cerebral tissue after the treatment. The levels of CIRI-induced increase of mNSS and CIRI-induced decrease of the number of Nissl bodies in the EA+VEGF group were respectively remarkably lower or higher than those of the simple EA and simple VEGF groups (P<0.05). WB and PCR showed that the expression levels of ATF 6, IRE 1, XBP1 and CHOP proteins and genes were notably higher in the model group than in the sham operation group (P<0.05), and considerably lower in the EA, VEGF and EA+VEGF groups than in the model group (P<0.05). Comparison among the three treatment groups showed that after the treatment, the expression levels of ATF 6, IRE 1, XBP1 and CHOP proteins and genes were obviously lower in the EA+VEGF group than in the EA and VEGF groups (P<0.05). EA and EA plus intracerebral microinjection of VEGF can improve neurological function and promote cerebral tissue repair in CIRI rats, which is associated with their effects in down-regulating the expression of ERS related proteins ATF 6, IRE 1, XBP1 and CHOP. The effect of EA+VEGF is superior to that of simple EA and simple VEGF.